Process for the manufacture of staple fiber



Patented Aug. 17, 1937 waste PATENT OFFICE PROCESS FOR THE MANUFACTURE OF STAPLE FIBER Leo Ubbelohde, Berlin-Charlottenburg, Germany No Drawing. Application April 25, 1935, Serial No. 18,212. In Germany February 10, 1931 Claims.

This application is a continuation in part of my application Ser. No. 590,779 of February 3rd 1932, now Patent No. 2,054,208. 7

This invention concerns staple fiber, that is 5 a textile fiber which is obtained from artificial silk by cutting it into short pieces which may be combed and spun like natural fibers. Ordinarily staple fiber was mixed with natural fibers since staple fiber alone cannot be spun without great difficulties. Its surface is perfectly smooth so that the single fibers do not adhere to each other.

They have no textile properties.

The present invention relates to a process for improving the textile properties of staple fiber.

More especially the invention refers to improve the surface of the fibers and to give them substantially the characteristics of ordinary textile fibers during combing and spinning operations.

According to the invention, ordinary spinning solutions which are used in the manufacture of artificial silk, for instance viscose, copper oxide, ammonia cellulose or a solution of cellulose esters within organic solvents, are used. These solutions are thoroughly mixed with irregular shaped sharp edged substances. This mixture represents a dispersion of such substances within the spinning solution. Of course, such substances must be insoluble within the spinning solution and should have a size not larger than the orifices used in extruding the solution into the precipitating medium. 7 I

I prefer infusorial earth which is of a very irregular shape and has sharp edges and points and which therefore has proved very suitable in my process. Moreover infusorial earth is a very cheap material which is found in large quantities in nearly every country. Besides this material, powder of glass, carborundum, ground brick or porcelain and other brittle materials which show 40 sharp edges and an irregular shape when divided to powder can be used.

As to the size of the particles of the powder, it depends from the titre or from the section area of the single fiber. Individual particles of a pig- 45 ment size as hitherto used for delustring artificial silk are ineffective for producing roughness and improving staple fiber. Such pigments are of submicroscopical individual size and much smaller than one micron.

Generally, the individual size of the particles should be at least one micron. In fibers of 2 deniers a size of 4 microns has been proved very 1 suitable, in fibers of 3 deniers 6 microns, in fibers I of 4 deniers a size of 7 microns, in fibers of 5 55 deniers 8 microns, 9 microns in fibers of 7 deniers or 11 microns in fibers of 10 deniers are effective. The size Varies up and down according to the denier of the single fiber. Certain variations are also necessary according to the shape of the section of the fiber. A regular circular section re- 5 quires a somewhat larger and an irregular serrated section requires a smaller size. The above indicated numbers are calculated for a normal viscose silk which is precipitated by an ordinary precipitating bath and shows about a circular section.

The effect consists in that the particles penetrate through the surface of the fiber while such is precipitated and shrinks in section, or that a great number of protuberances or lumps are caused in the surface which shows therefore rough properties. The behaviour of the fiber is like a natural fiber. It maybe treated viz.,' combed and spun like cotton or wool Without any waste and produces a yarn of ordinary tensile strength for the spun fibers adhere firmly together by reason of their roughness. I

The effect may be graduated by varying the quantity of the admixed powder.

A certain roughem'ng effect can be stated in using 12% of powder calculated on the cellulose weight. Ordinarily a medium percentage of 5%, calculated on the weight of the dissolved cellulose, has a very good result. In the production of course fibers say of 8-12 deniers I prefer'a percentage of 10%. The maximal content should be 20%.

The process may be illustrated by the following examples without limiting the scope of my invention.

35 Example 1 Emwmple 2 To obtain fibers of four deniers from a cuprammonium solution of 8% cellulose, the solution is mixed with 5% of infusorial earth calculated on the weight of the cellulose. The particles have a maximal size of seven microns.

The mixture is spun into an ordinary precipitating bath of soda lye. The freshly spun threads are acidified with diluted sulphuric acid' to remove the copper, Washed, soaped, dried and finally cut into short fibers. The fibers show an extreme roughness like natural wool.

Example 3 For some purposes of the textile industry course titers are used. Fibers of 12 deniers are obtained by mixing an ordinary. viscose solution of 9%' cellulose with 10% :powdered porcelain calculated on the weight of the cellulose. The single particles have a maximal size of 12 microns. Instead of. porcelain, powdered glass, carborundum, brick or the like may be used. The solution is precipitated and the threads finished and out according to Example 1. The obtained fibers can be spun like ordinary natural fibers whilst hitherto coarse staple fibers of such a denier could not be spun without a relativel high admixture of natural fibers.

Example 4 To obtain a fiber of 3 deniers from a solution tion. containing sharp edged substances selected from a group consisting of infusorial earth, ground glass, carborundum, brick and porcelain,

said substances being of a particle size andin such an amount as to produce protuberances and lumps on the surface of the extruded fibers.

2.,In a'process forthe manufacture of staple fibers, the step of extruding a cellulose solution containing irregular sharp edged particles of infusorial, earth, said particles being of. a size and .in such a quantity as' to form protuberances and lumps on the surface of said fibers.

' 3. In a process for the manufacture of staple 'fibers, the step of 'extruding a' cellulose solution containing irregular sharp edged particles of ground glass; said particles being of a size and in such a quantity as to form'protuberances and lumps on the surface of said fibers.

4. In a process for the manufacture of staple fibers, the-step of extruding a cellulose solution containing irregular sharp edged particles ,of brick, said particles being'of a size and in such a quantity as to form protuberances and lumps on the surface of said fibers.

'5. An vartificial fiber comprising a mixture of cellulosic material and insoluble sharp edged particles, said particles being substantially equal- 1y: dispersed within said material, said particles being of such a size and such an amount as' to 'form protuberances and lumps on the surface of the fiber, said particles being seiected from a group consistingof infusorial earth, ground glass,

oarborundum, brick and porcelain.

LEO: UBBELOl-I D E. V 

